GH-1196: Write NO_COMPRESSION_LENGTH sentinel for empty buffers in compress()

[PG1204]

What's Changed

AbstractCompressionCodec.compress() wrote a length prefix of 0 for empty buffers. The Arrow IPC compression format only defines a positive length (compressed) or -1 / NO_COMPRESSION_LENGTH (stored uncompressed); a 0 prefix is undefined. As a result, C++/PyArrow reject Java-produced streams that contain empty buffers, even though Java itself accepts them on read.

This changes the empty-buffer shortcut in compress() to write CompressionUtil.NO_COMPRESSION_LENGTH (-1) instead of 0.

decompress() is intentionally left unchanged:

• its NO_COMPRESSION_LENGTH branch handles the new output, and
• its decompressedLength == 0 branch remains for backward-compatible reads of older Java-produced streams.

Added a parameterized test (testEmptyBufferWritesUncompressedSentinel, covering LZ4 and ZSTD) that compresses an empty buffer, asserts the prefix equals NO_COMPRESSION_LENGTH, and asserts it round-trips back to a zero-length buffer. The pre-existing testEmptyBuffer continues to pass with empty buffers now routed through the -1 path.

Closes #1196.

[PG1204]

Notes for reviewers

• Empty-buffer path uses setLong(0, ...) directly, not the endianness-aware writeUncompressedLength(). This is safe: reverseBytes(-1) == -1, so the sentinel reads back correctly on big-endian too. It also matches the existing code, which wrote 0 the same way.
• Test ownership: with the -1 sentinel, decompress() now routes through the NO_COMPRESSION_LENGTH branch -> extractUncompressedBuffer(), which returns a slice sharing the compressed buffer's reference manager. The test closes only the decompressed slice (which releases the shared allocation); closing the original compressed buffer as well would be a double-free. Verified leak-free via the RootAllocator check in @AfterEach.

[lidavidm]

Seems reasonable to me.

[lidavidm]

@PG1204 can you rebase to pick up CI fixes?

[PG1204]

@PG1204 can you rebase to pick up CI fixes?

@lidavidm rebase done.